JPH06160840A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To restrain a liquid crystal panel from being heated and to make the light utilization efficiency of a back light high. CONSTITUTION:Light emitted from a lamp 1 is condensed by a lamp house 5; furthermore, is efficiently made incident on a polarizing means 3 by using such a condensing means 8 as a prism, and is divided into components having different polarizing surfaces, then one light beam is aligned with the polarizing surface of the other light beam, and the light beam is made to emit to the liquid crystal panel by a reflecting board 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back lighting means such as a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, an edge for emitting light from a flat surface of a light guide plate by using a rod-shaped light source as a back illuminating means of a liquid crystal display device to cause light from a lamp to enter an end face of a light guide plate disposed on the back surface of the liquid crystal display device. A backlight structure called a light type is adopted.

[0003]

The above-mentioned edge light type backlight is mainly used for liquid crystal display devices for portable electronic devices, but this is for the purpose of making the electronic device lighter, thinner and shorter and saving power. There is.

However, the following problems remain. That is, in the liquid crystal panel of the liquid crystal display device, the first polarizing plate is disposed on the glass plate on which light is incident, and the light transmitted through the polarizing plate is further transmitted through the liquid crystal and the second polarizing plate, and then the image is displayed. Is displayed as.

The maximum transmittance of the first polarizing plate is 50% at the maximum, the light utilization efficiency of the backlight is 1/2 or less, and the light that does not pass through the first polarizing plate becomes heat and becomes a liquid crystal panel. It was causing a temperature rise problem.

As a means for solving this problem, use of a beam splitter for pre-polarizing light is considered. However, in the rod-shaped light source, since the spread angle of light is large, the performance of the beam splitter is deteriorated.

[0007]

The present invention is intended to solve the above problems.

According to a first aspect of the present invention, there is provided a liquid crystal panel, a light-transmitting light guide plate having a transparent surface on one surface and a reflecting means on the other surface opposite to the liquid crystal panel, and one end surface portion of the light guide plate. A bar-shaped light source, a means for condensing light emitted from the bar-shaped light source in one direction, and a polarizing means for polarizing the light from the bar-shaped light source between the bar-shaped light source and the one end face portion of the light guide plate. According to a second aspect of the present invention, the light utilization efficiency is increased by a means for aligning light of other polarization directions not used in the type of the first aspect in the same polarization direction.

According to the third and fourth aspects, a means such as a lens or a prism is arranged between the rod-shaped light source and the beam splitter to collimate or condense the light, thereby enhancing the performance of the polarization beam splitter. And claim 5
Is to increase the light collection efficiency by allowing the light emitted from the light source, especially on the rear side, to circulate around the light source due to the diffusion effect, thereby increasing the light utilization efficiency.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific structure of the liquid crystal display device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the liquid crystal display device of claim 1 according to the present invention, and FIG.
FIG. 4, FIG. 4, FIG. 5, and FIG. 5 are sectional views of a conventional liquid crystal display device.

In FIG. 1, 1 is a lamp, 2 is a reflector,
3 is a polarizing means, 101 is a first polarizing plate, 102 is a second polarizing plate, and 103 and 104 are glass substrates holding liquid crystals.

In FIG. 1, the light emitted from the lamp 1 is collected by a condenser plate 5, is incident on a polarizing means 3, and is separated into a P-polarized component and an S-polarized component. Only the P-polarized component is reflected by a reflector 4 on the liquid crystal panel side. It is used to emit the S-polarized light component, and the S-polarized component is discharged to the outside.

In FIG. 2, the S-polarized light component which is not used in the method shown in FIG. 1 is reflected by the reflection plate 3-1 and the polarization planes are aligned by the optical rotation means 7 to be used as the same polarization component (P component). .

FIG. 3 shows an embodiment in which a condensing means 8 such as a prism is arranged before the polarizing means of the method shown in FIG.

FIG. 4 shows an embodiment in which a diffusing means 9 is added to the light collecting plate 5 to improve the light collecting efficiency.

[0017]

As described above, according to the present invention, it is possible to suppress the heat generation of the liquid crystal panel and further improve the light utilization efficiency.

[Brief description of drawings]

FIG. 1 is an embodiment showing an edge light type liquid crystal lighting device according to claim 1.

FIG. 2 is an embodiment showing an edge light type liquid crystal lighting device of claim 2;

FIG. 3 is an embodiment showing an edge light type liquid crystal lighting device according to claim 4;

FIG. 4 is an embodiment showing an edge light type liquid crystal lighting device according to claim 5;

FIG. 5 is an example showing a conventional edge light type liquid crystal lighting device.

[Explanation of symbols]

 1 Lamp 2 Reflecting Plate 3 Polarizing Beam Splitter 4 Reflecting Plate 5 Condensing Plate 6 Diffusing Plate 7 Wavelength Plate 8 Prism 9 Diffusing Means 101 First Polarizing Plate 102 Second Polarizing Plate 103 Glass Substrate 104 Glass Substrate 105 Light Guide Plate

Claims (5)

[Claims] 1. A liquid crystal panel, a light-transmissive light guide plate having a transparent surface on one side and a reflecting means on the other surface side opposite to the liquid crystal panel, and one end surface portion of the light guide plate. A rod-shaped light source, means for converging light emitted from the rod-shaped light source in one direction, and polarizing means for polarizing the light from the rod-shaped light source between the rod-shaped light source and the one end face portion of the light guide plate. A liquid crystal display device characterized by the above. 2. The liquid crystal according to claim 1, wherein the polarization means divides the light into two polarized light beams having different polarization directions and polarizes one light beam so as to match the other polarization direction. Display device. 3. The liquid crystal display device according to claim 1, further comprising means for collimating the light of the rod-shaped light source between the rod-shaped light source and the polarizing means. 4. The liquid crystal display device according to claim 1, further comprising means for condensing light from the rod-shaped light source between the rod-shaped light source and the deflection means of the liquid crystal display device. 5. The liquid crystal display according to claim 1, wherein the means for converging the light emitted from the rod-shaped light source of the liquid crystal display device in one direction includes means for diffusely reflecting the light on the back side of the light source. apparatus.